The statements in this section merely provide background information related to the present disclosure. Accordingly, such statements are not intended to constitute an admission of prior art.
Powertrain systems may be configured to transfer torque originating from multiple torque actuators through a torque transmission device to an output member that can be coupled to a driveline. Such powertrain systems include hybrid powertrain systems and extended-range electric vehicle systems. Control systems for operating such powertrain systems operate the torque actuators and apply torque transfer elements in the transmission to transfer torque in response to operator-commanded output torque requests, taking into account fuel economy, emissions, driveability, and other factors. Exemplary torque actuators include internal combustion engines and non-combustion torque machines. The non-combustion torque machines may include electric machines that are operative as motors or generators to generate a torque input to the transmission in conjunction with or independently of a torque input from the internal combustion engine. The torque machines may transform vehicle kinetic energy transferred through the vehicle driveline to electrical energy that is storable in an electrical energy storage device in what is referred to as a regenerative operation. A control system monitors various inputs from the vehicle and the operator and provides operational control of the hybrid powertrain, including controlling transmission operating range and gear shifting, controlling the torque actuators, and regulating the electrical power interchange among the electrical energy storage device and the torque actuators to manage outputs of the transmission, including torque and rotational speed.
Known multi-mode electrically-variable transmissions (EVTs) can be configured to operate in one or more fixed-gear ranges, one or more electric vehicle (EV) ranges, one or more electrically-variable transmission (EVT) ranges, and one or more neutral ranges. A zero torque output from one of the torque machines may be desirable while operating in one of the transmission ranges due to a commanded neutral condition, in response to a derated torque output of the torque machine, and in response to a fault associated with operation of the torque machine.